A Synthetic Aperture Radar (SAR) is a microwave imaging radar, and it may be mounted on a flying platform such as an aircraft, a satellite and a spacecraft to implement all-time all-weather observation on the ground, and has a certain ground penetration capability. Therefore, an SAR system has unique advantages in applications to aspects of disaster monitoring, resource exploration, marine monitoring, environmental monitoring, general investigation and yield estimation of crops, surveying and mapping, military reconnaissance and the like, may realize functions difficult for other remote sensing means to realize, and is applied to the fields of civil applications and national defense more and more.
A Bi-satellite formation SAR system is an important new-concept space-based radar system, and the system carries radars on satellites flying in a formation to form a bistatic/multi-static radar system to complete tasks of wide-swath high-resolution imaging, ground elevation measurement, ocean current velocity measurement, ground moving target detection and the like. Bi-satellite formation interference is implemented in a manner that a primary satellite transmits a signal and the primary and secondary satellites simultaneously receive signals. Since the primary and secondary satellites use different crystal oscillators, an azimuth phase error introduced by a crystal oscillator frequency error may exist, and is accumulated along with time. On the other hand, transmitting and receiving phases are unrelated in noise, a low-frequency phase noise component may not be canceled like a single-station condition, and an echo domain phase error generated by phase asynchrony may influence imaging focusing and interferometric phase accuracy, so that phase synchronization is required.
In a present related technology, during phase synchronization, a radar signal is stopped to be sent after the radar signal is transmitted, a dedicated phase synchronization signal is transmitted further for subsequent phase synchronization, and a carrier frequency of the phase synchronization signal is different from a carrier frequency of the radar signal. Therefore, not only may normal work of a radar be interrupted to reduce working efficiency of the radar, but also complexity in system design may be increased because the carrier frequency of the phase synchronization signal is different from the carrier frequency of the radar signal. In addition, the carrier frequency is different from the carrier frequency of the radar signal, and then obtained synchronization data is required to be converted into a magnitude of a frequency of the radar according to a proportion for phase compensation, so that compensation accuracy is reduced.